The recording systems of magnetic read/write devices include a longitudinal magnetic recording system wherein signals are magnetized in the direction along the surface of the recording medium (the longitudinal direction), and a perpendicular magnetic recording system wherein signals are magnetized in the direction perpendicular to the surface of the recording medium. It is known that the perpendicular magnetic recording system is harder to be influenced by thermal fluctuation of the recording medium and capable of implementing higher linear recording density, compared with the longitudinal magnetic recording system. Therefore, perpendicular magnetic recording is a promising recording technique in which magnetic data bits on a magnetic recording disk are defined, such that their magnetic moments are perpendicular to the plane of the magnetic recording disk. The progress to perpendicular recording from longitudinal recording is seen as one of the advances that will allow the continued increase in data densities on magnetic recording disks in the future. In such a magnetic disk system based on perpendicular magnetic recording, a single-pole type magnetic head including a main pole having a pole face facing the magnetic disk and an auxiliary pole are used.
A slider of the perpendicular recording method has a thin film coil for generating a magnetic flux and a magnetic pole layer extending rearward from an air bearing surface and emitting the magnetic flux generated by the thin film coil toward a recording medium. The magnetic pole layer includes, for example, a track width specifying part having a width (uniform width) specifying the recording track width of a recording medium. The height of the track width specifying part in the magnetic pole layer, that is, the distance from the front end (the edge exposed in the air bearing surface) of the track width specifying part to the rear end (the edge on the side far from the air bearing surface) is a Neck Height as an important factor contributing to recording performances of the slider. In the slider of the perpendicular recording method, when current is passed to a thin film coil and a magnetic flux for recording is generated, the magnetic flux is emitted from the tip of the track width specifying part of the magnetic pole layer, thereby generating a magnetic field for recording (perpendicular magnetic field), and the surface of the recording medium is magnetized on the basis of the perpendicular magnetic field. In such a manner, information is magnetically recorded on the recording medium.
In a process of manufacturing the slider, the magnetic head structure is cut in rows of the magnetic head precursors, thereby obtaining a plurality of magnetic head row bars. After that, one end face (a cut face of the magnetic head structure) of the magnetic head row bar is polished so that the dimension of each polished recording head portion becomes a predetermined dimension, concretely, the neck height of the recording head portion becomes a predetermined dimension thereby forming an air bearing surface. After that, the magnetic head row bar in which the air bearing surfaces are formed is cut magnetic heads, thereby obtaining a plurality of sliders.
To assure operation performance of the thin film magnetic head, it is necessary to determine the neck height contributing to the recording performance with high precision, which are defined in the lapping process. The geometric shape of the main pole face close to the media surface affects the properties of a magnetic field for recording, it is required the main pole face of all magnetic heads with a high accuracy geometric shape to perform uniform recording performance. Due to the above-mentioned main pole structure, the main pole face geometric is sensitively related with the neck height. If the neck height was longer, the geometric shape of the main pole face will be smaller, if the neck height was shorter, the geometric shape of the main pole face will be bigger correspondingly. Based on this reason, in order to obtain the uniformed main pole face geometric shape, it is needed to detect the accurate lapping stop point during magnetic head manufacturing. Actually, the final pole face is formed by a precision lapping process. To know lapping stop at right point will be critical to form accurate main pole geometric shape, and it is a major task for the perpendicular magnetic head lapping process.
Controlling the lapping process is typically achieved through the use of electrical lapping guides (ELGs) which are placed in multiple locations on the magnetic head row bar. Traditionally, an ELG is a metal layer deposits between two sliders, while the ELG is placed on the slider in the improved technology recently. In some instances, the slider may also include one or more ELGs. The ELG has a resistance that varies as the material is removed during a lapping process and thus may be used to monitor lapping during slider manufacturing. Lapping the ELG causes the electrical resistance to increase. Thus, by monitoring the ELG along the row bar and adjusting the pressure being applied to the row bar at different locations along its length, lapping process can be controlled. Lapping process is terminated when the ELG resistance reaches the threshold value. However, the using of the ELG is such limited for lapping process. Another technology is described in U.S. Pat. No. 7,336,442, in which indicator members are used. The row bar for lapping process has two indicator members disposed therein, with one being a regular triangle and the other being inverted triangle. The main pole and the indicator members are lapped synchronously, and the lapping process is terminated when the shape of the lapping surface of the regular triangle and the inverted triangle are identical. Owing to the structure difference between the indicator members and the main pole, when the shapes of the lapping surface of two triangles are identical, the wide of the main pole dose not always reach the predetermined width, and in turns, the accurate lapping vale is not available in next process. Furthermore, because testing the lapping surface of the regular triangle and the inverted triangle while being lapped is not available, the lapping process is just based on the experience of the skilled to determinate the terminated time, so it could not be accurate enough. Hence, the there is a limited to the lapping process using the said indicators.
Accordingly, a need has arisen for providing an improved row bar for forming sliders and the method of manufacturing the slider, which is accurate enough to achieve improvement of the slider performance, and to overcome the above-mentioned drawbacks.